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Encephalitis

What is encephalitis?

Encephalitis: the acute infection and inflammation of the brain.

Encephalitis is generally a virus caused illness. A very common way the virus is spread is by mosquito. The equine (horse), La Crosse, Japanese, West Nile, and St. Luis encephalitis are all caused by mosquito.
*although most commonly caused by viruses, it can also be caused by bacteria, fungi, and parasites*

The illness lasts an average of 2-3 weeks. It can be a very mild illness to a life-threatening one, there is a 30% death rate from Arboviruse cases.
*The 30% death rate comes from the CDC fact sheet, but they report it is hard to guess the amount of deaths, and the spread of the disease, because it is greatly underreported because it resembles the flu*
*An Arboviruse is a family of viruses carried by insects and ticks*

Chart of the Encephalitis Virus


Disease
Geographic Location
Vector/ Hosts
Comment
Herpes encephalitis
United States/The world
Human-to-human
contact

Prompt treatment with acyclovir
increases survival to 90
%

West Nile encephalitis
Africa, West Asia, Middle East, United States
Mosquito/mostly birds
Majority are mild cases. Less than 1% of those infected will become severely ill. Full recovery expected. Vaccine for humans tested late 2002.
Eastern equine
encephalitis

East Coast (from
Massachusetts to Florida),
Gulf Coast

Mosquito/ Birds
Often occurs in horses. High
mortality rate (50-75%);
frequent outcomes (seizures, slight paralysis), especially
in children

Western equine
encephalitis

Western United States and
Canada

Mosquito/ Birds
Often occurs in horses.
Particularly affects infant
s

Venezuelan equine
encephalitis

Western Hemisphere
Mosquito/ Rodents
Rare in United States; low
mortality rate, rare after-effects

La Crosse encephalitis
Throughout the United States,
especially in Midwestern &
Southeastern regions

Mosquito/ Chipmunks,
Squirrels

Most common cause of
encephalitis in children younger
than 16 years old

St. Louis encephalitis
Midwestern & Mid-Atlantic
United States

Mosquito/ Birds
Mostly affects adults
Japanese encephalitis
Temperate Asia, southern
and southeastern Asia

Mosquito/ Birds and pigs
Vaccine available. See
Prevention section.
High morbidity/mortality rates

Symptoms
v Fever
v Fatigue
v Sore Throat
v Stiff neck and Back
v Vomiting
v Headache
v Confusion
v Irritability
v Unsteady gait
v Drowsiness
v Visual sensitivity to light

More severe symptoms
v Seizures
v Muscle weakness
v Paralysis
v Memory loss
v Sudden impaired judgment
v Poor responsiveness


If you develop any sign or symptoms of this, please go contact your doctor immediately. Do not hesitate because you think this is just flu. Severe symptoms can require emergency medical attention.